diff options
| author | Eric Dumazet <edumazet@google.com> | 2026-01-07 21:22:50 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-01-17 16:35:30 +0100 |
| commit | 949647e7771a4a01963fe953a96d81fba7acecf3 (patch) | |
| tree | e59ed404b4c167fbb40a4c2d6572d92aed46bde6 | |
| parent | d93ba83fc3f5b9a8314ba7b8f633aac7ffb92107 (diff) | |
arp: do not assume dev_hard_header() does not change skb->head
[ Upstream commit c92510f5e3f82ba11c95991824a41e59a9c5ed81 ]
arp_create() is the only dev_hard_header() caller
making assumption about skb->head being unchanged.
A recent commit broke this assumption.
Initialize @arp pointer after dev_hard_header() call.
Fixes: db5b4e39c4e6 ("ip6_gre: make ip6gre_header() robust")
Reported-by: syzbot+58b44a770a1585795351@syzkaller.appspotmail.com
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260107212250.384552-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | net/ipv4/arp.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index 833f2cf97178..3ce1664e8632 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -564,7 +564,7 @@ struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, skb_reserve(skb, hlen); skb_reset_network_header(skb); - arp = skb_put(skb, arp_hdr_len(dev)); + skb_put(skb, arp_hdr_len(dev)); skb->dev = dev; skb->protocol = htons(ETH_P_ARP); if (!src_hw) @@ -572,12 +572,13 @@ struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, if (!dest_hw) dest_hw = dev->broadcast; - /* - * Fill the device header for the ARP frame + /* Fill the device header for the ARP frame. + * Note: skb->head can be changed. */ if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0) goto out; + arp = arp_hdr(skb); /* * Fill out the arp protocol part. * |